Host: The questioner says, ‘The Imaam of a mosque forgets to recite al-Faatihah in a rak’ah, he only remembers whilst he is [actually] in rukoo’, what should he do?
Al-Albaani: He cancels the rukoo’ and stands up and reads al-Faatihah and then carries on with the prayer, he cancels the rukoo’, cuts it off and stands up straight away and recites al-Faatihah … and if it is the first or second rak’ah he reads a Surah or part of one [after Faatihah] and then bows and continues the prayer.
Someone Else: [What about] the people praying behind him, O Shaikh of ours?
Al-Albaani: They do as he does.
Questioner: They follow him?
Al-Albaani: “The Imaam is [appointed] to be followed …” [Bukhaari and others]
Al-Hudaa wan-Noor, 190.